Unable to Check Google Mail from Outlook

I struggled for a week trying to setup up google mail with a custom domain to work with Outlook. I kept getting an unable to login message from the Outlook client, despite following the instructions on Google’s site (and numerous help sites) to the letter.
The issue is that there is an unmentioned setting buried in the Google account settings that no one bothers to mention. A few things contribute to this being so difficult to resolve.
1) The Outlook Message that appears has an unwieldy message in it. Something like:

"Outlook" returned the error "[WEBALERT https://accounts.google.com/ContinueSignIn?sarp=1&scc=1&plt=AKgnsbsf9BRPXiXd1yvu5M36vG9QWGxTq9VB8dFkoAw7jffOj0T64i3l-fHE4UmGycJhTpODUjDkK8SxX7Qamz0McnzZOuIsq0HPZGNIJab1cSSuvK0Ord49yXumEMy_NEpd1LQe57KKPrl9DOhZ0h1YKZgAJ67ESaH15WP3DlWsSgsV3dXjlrVgR3xDRUrL1xRlXlgQr0vkBokv_dTXQzVY8UXL_qtDMw] Web login required.." Your username/password or security settings may be incorrect. Would you like to try re-entering your password?